KTLS: Check for unprocessed receive records in ktls_configure_crypto.

KTLS implementations currently assume that the start of the in-kernel
socket buffer is aligned with the start of a TLS record for the
receive side.  The socket option to enable KTLS specifies the TLS
sequence number of this initial record.

When read ahead is enabled, data can be pending in the SSL read buffer
after negotiating session keys.  This pending data must be examined to
ensurs that the kernel's socket buffer does not contain a partial TLS
record as well as to determine the correct sequence number of the
first TLS record to be processed by the kernel.

In preparation for enabling receive kernel offload for TLS 1.3, move
the existing logic to handle read ahead from t1_enc.c into ktls.c and
invoke it from ktls_configure_crypto().

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17942)

1 files changed, 3 insertions, 63 deletions

diff --git a/ssl/t1_enc.c b/ssl/t1_enc.c
index 101cba6490..11c663e16d 100644
--- a/ssl/t1_enc.c
+++ b/ssl/t1_enc.c
@@ -98,42 +98,6 @@ static int tls1_generate_key_block(SSL *s, unsigned char *km, size_t num)
     return ret;
 }
 
-#ifndef OPENSSL_NO_KTLS
- /*
-  * Count the number of records that were not processed yet from record boundary.
-  *
-  * This function assumes that there are only fully formed records read in the
-  * record layer. If read_ahead is enabled, then this might be false and this
-  * function will fail.
-  */
-# ifndef OPENSSL_NO_KTLS_RX
-static int count_unprocessed_records(SSL *s)
-{
-    SSL3_BUFFER *rbuf = RECORD_LAYER_get_rbuf(&s->rlayer);
-    PACKET pkt, subpkt;
-    int count = 0;
-
-    if (!PACKET_buf_init(&pkt, rbuf->buf + rbuf->offset, rbuf->left))
-        return -1;
-
-    while (PACKET_remaining(&pkt) > 0) {
-        /* Skip record type and version */
-        if (!PACKET_forward(&pkt, 3))
-            return -1;
-
-        /* Read until next record */
-        if (!PACKET_get_length_prefixed_2(&pkt, &subpkt))
-            return -1;
-
-        count += 1;
-    }
-
-    return count;
-}
-# endif
-#endif
-
-
 int tls_provider_set_tls_params(SSL *s, EVP_CIPHER_CTX *ctx,
                                 const EVP_CIPHER *ciph,
                                 const EVP_MD *md)
@@ -201,12 +165,7 @@ int tls1_change_cipher_state(SSL *s, int which)
     int reuse_dd = 0;
 #ifndef OPENSSL_NO_KTLS
     ktls_crypto_info_t crypto_info;
-    unsigned char *rec_seq;
     void *rl_sequence;
-# ifndef OPENSSL_NO_KTLS_RX
-    int count_unprocessed;
-    int bit;
-# endif
     BIO *bio;
 #endif
 
@@ -473,30 +432,11 @@ int tls1_change_cipher_state(SSL *s, int which)
     else
         rl_sequence = RECORD_LAYER_get_read_sequence(&s->rlayer);
 
-    if (!ktls_configure_crypto(s, c, dd, rl_sequence, &crypto_info, &rec_seq,
-                               iv, key, ms, *mac_secret_size))
+    if (!ktls_configure_crypto(s, c, dd, rl_sequence, &crypto_info,
+                               which & SSL3_CC_WRITE, iv, key, ms,
+                               *mac_secret_size))
         goto skip_ktls;
 
-    if (which & SSL3_CC_READ) {
-# ifndef OPENSSL_NO_KTLS_RX
-        count_unprocessed = count_unprocessed_records(s);
-        if (count_unprocessed < 0)
-            goto skip_ktls;
-
-        /* increment the crypto_info record sequence */
-        while (count_unprocessed) {
-            for (bit = 7; bit >= 0; bit--) { /* increment */
-                ++rec_seq[bit];
-                if (rec_seq[bit] != 0)
-                    break;
-            }
-            count_unprocessed--;
-        }
-# else
-        goto skip_ktls;
-# endif
-    }
-
     /* ktls works with user provided buffers directly */
     if (BIO_set_ktls(bio, &crypto_info, which & SSL3_CC_WRITE)) {
         if (which & SSL3_CC_WRITE)